Jon Sneyers Peter Van Weert Tom Schrijvers Leslie De Koninck As time goes by: Constraint Handling Rules - A survey of CHR research from 1998 to 2007 http://arxiv.org/abs/0906.4474 2009 CoRR abs/0906.4474 db/journals/corr/corr0906.html#abs-0906-4474 informal publication